21503133 has 12 divisors (see below), whose sum is σ = 31112640. Its totient is φ = 14311176.

The previous prime is 21503129. The next prime is 21503149. The reversal of 21503133 is 33130512.

It is not a de Polignac number, because 21503133 - 2² = 21503129 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21503033) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4810 + ... + 8132.

It is an arithmetic number, because the mean of its divisors is an integer number (2592720).

Almost surely, 2^21503133 is an apocalyptic number.

It is an amenable number.

21503133 is a deficient number, since it is larger than the sum of its proper divisors (9609507).

21503133 is a wasteful number, since it uses less digits than its factorization.

21503133 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4048 (or 4045 counting only the distinct ones).

The product of its (nonzero) digits is 270, while the sum is 18.

The square root of 21503133 is about 4637.1470755196. The cubic root of 21503133 is about 278.0783942948.

Adding to 21503133 its reverse (33130512), we get a palindrome (54633645).

The spelling of 21503133 in words is "twenty-one million, five hundred three thousand, one hundred thirty-three".